I need help with my Samsung Gravity T by T-Mobile?

[ali9692]

I had my phone on my lap and my brother decided to tackle me on the ground and I guess one of us touch the screen and pressed something ( it's a touch screen ) and it made the font really small on the texts I get . Can someone please help me . I tried tapping it and stuff but it doesn't work and the manual doesn't help any either . Someone please help !